How to send data from angular?

Question

Here is my code

Product interface

export interface Product{
    _id?:string,
    name?:string,
    price?:number;
    quantity?:number;
    tags?:Tags[];
    files?: File[];
}

temp.component.ts->the function in component file to use service to send data

export interface Tags {
  name: string;
}

constructor(private appService:AppService){

}

submit(){
  this.product_decided = {
    name: this.product.value.name,//string
    price:this.product.value.price,//string
    quantity:this.product.value.quantity,//string
    tags:this.product.value.tags,//TAGS[]
    files:this.files//FILES[]
  }
  this.appService.create_product(this.product_decided).subscribe();
}

Here is my AppService

export class AppService{
   private userUrl = "http://localhost:5000/"
   constructor(private http:HttpClient){}

   create_product(product:Product){
      return this.http.post<Product(this.userUrl,JSON.stringify(product);
   }
}

Here is my product.console Json stringify converts everything to string but my files are NULL.

Is there any way to upload this product_decided to using HTTP.